The Pocket Guide to the Polyvagal Theory and The Body Remember, Vol. 2.

The Pocket Guide to the Polyvagal Theory: The Transformative Power of Feeling Safe

by Stephen Porges (Norton, 2017)

The Body Remembers, Volume Two: Revolutionizing Trauma Treatment

by Babette Rothschild (Norton, 2017)

I have been enjoying these latest new resources for understanding the autonomic nervous system (ANS), and I am inspired to create a plea to the experts to tweak the message. In my view, the issues are:

  1. Whether the “social engagement system,” as identified and defined by Stephen Porges, is really “parasympathetic.”

  2. Whether “ventral vagal” is a useful synonym for the Polyvagal Theory’s “social engagement system.”

Both of these books are excellent. Porges has downscaled his scientific writing style to make his game-changing information accessible for laypeople and allied professionals. Rothschild has organized an updated autonomic understanding into a comprehensive summary including a very helpful wall chart. This “Volume Two” follows her previous (2000 and following, via several different titles) explanation of body-centered approaches to resolving trauma. There is a lot to like in both these books and both are highly recommended. My comments here are not intended to discourage readers from either book, at all.

But I do have a couple of discussion points to offer:

Firstly, I question the inclination to categorize the newly-discovered functions as parasympathetic, which both books clearly state. It is convenient to use the parasympathetic term, since the new and old autonomic* branches both down-regulate the heart, are located immediately next to each other (in the case of Cranial Nerve X, the Vagus) and their categorization is so well-established in every textbook and reference. However the new branch has millions of years of phylogenic separation from the old (modern primates versus primitive aquatic vertebrates), has a distinct and different function (protection of vulnerable newborn via maternal bonding versus baseline metabolism), and has a quite different anatomical configuration (myelinated versus unmyelinated). To me these differences are so significant that the co-location and similar down-regulation aspects are secondary.

Perhaps the categorization as parasympathetic is just an artifact of misidentification long ago, before the subtle difference between dorsal (Dorsal Motor Nucleus) and ventral branches (Nucleus Ambiguus) had been discovered by Porges. The nerves exit the brainstem at the same point, and someone in medieval times decided to call the whole bunch “Vagus” without differentiating between the two. It is very hard to overturn a designation of this kind once it has become established.

In addition, the categorization as parasympathetic allows the authors to sidestep the problem of what to do about the prevailing understanding of the ANS as a reciprocal, dualistic arrangement. This notion is so well-established (“fight or flight versus rest and rebuild” is a universal, wrong idea) that to propose something different would be scientific heresy and risk distracting from proper evaluation of the whole Polyvagal Theory. Porges includes a fascinating summary of the stages of his career and one aspect that stood out for me is how he has had to constantly be on guard against the threat of the academic and scientific establishments that could easily damage his career if his findings were too far out of the mainstream. I found myself feeling grateful that I have been an “alternative” outsider throughout my 40-year career, relatively free of such concerns. Physicist Max Planck is paraphrased as saying “Science progresses one funeral at a time” as orthodoxy tends to strangle innovation; I think some of that effect is in play here, perpetuating a wrong idea just because it is the prevailing paradigm.

Functionally, Porges tells us there are three branches of the ANS, not two, and they are sequential (in phylogenic order from newest to older to most primitive) instead of being purely reciprocal. Porges asserts this three-part arrangement in some places but not in others. The idea of three branches may be just too audacious for a respected academic; to say it might distract orthodox readers from some of his most important findings. Rothschild takes the approach of making sub-categories, such as Parasympathetic 1-2-3, each describing different configurations; I think her nomenclature approach will be confusing for newcomers.

Secondly, I would like to see “ventral vagus” retired as a synonym for the social engagement system; Rothschild uses the phrase on her main chart and in her text, and I keep hearing this in other writers’ comments about the Polyvagal Theory. “Ventral vagus” refers to the myelinated Vagus strand originating in the Nucleus Ambiguus. However Porges has repeatedly stated that the ventral vagus is only one segment of the composite neural circuit that accomplishes social functions such as involuntary facial cues and sounds. Cranial Nerves V, VII, IX and XI also have important roles that have been thoroughly discussed by Porges. Yet I continue to hear “ventral vagus” used as the umbrella term for the whole system. The proper phrase would be the “corticobulbar tract,” that connects the nuclei of the relevant cranial nerves with important structures such as the amygdalae and the cerebral cortex. Alternatively, and my preferred terminology when I present this in classes, the whole system could be known as the “Social branch of the ANS,” since “corticobulbar” can be daunting for students and newcomers.

“Ventral vagus” is inevitably confusing for my audiences who tend to be less technical but deeply involved in the real world’s therapeutic trenches. The vagus nerve already has a well-known identity– innervating the viscera for baseline metabolism and immobilization stress responses. Students get thrown off when we use the same term to describe greatly different functions. In this case I think a distinct term would be better.

I have taught Polyvagal Theory to novices and beginners since about 2003. I think Porges’ discovery is a true revolution in health care, overturning several errors that have engendered damaging policies about birthing, infant care, childhood education and trauma therapies for more than a hundred years. However I foresee that adoption of the new understanding will be unnecessarily delayed if leaders in the field continue to perpetuate these two points of confusion. The world needs Polyvagal Theory to win universal acceptance and thereby create a sea change in policies, so anything that be done to ease the process will be very valuable.

Lastly, I would like to hear leaders in the field do more to differentiate “normal functions” from “stress responses.” These books continue the prevailing practice of not really stating this distinction plainly. My audiences have had “fight/flight versus rest/rebuild” drummed into them for so long that the apples-and-oranges problem (one is a stress response, the other is a normal function) is not noticed. It was a revelation for me to hear from Porges that the ANS branches have normal functions in the case of the sympathetic and stress responses in the case of the parasympathetic. I was taught “sympathetic bad, parasympathetic good” but the new Porges-informed reality is not so simple. The sympathetic is a higher order (phylogenically newer) of stress response than parasympathetic, and the implications for therapists are enormous; so many textbooks say “the goal of therapy is to induce a parasympathetic state,” but the parasympathetic stress response is actually much worse– in fact it is dangerous. Compared to the first two issues discussed above, addressing this problem is less urgent from my perspective, but since I am making a wish list, it deserves to be mentioned here.


*“Autonomic” means involuntary neural circuits that are essential for survival. Porges’ famous Phylogeny diagram focuses on heart regulation, showing the evolution of an increasingly sophisticated excitation/calming setup, with more modern creatures adding new equipment to enhance survival capabilities.

John ChittyComment